Reflecting unit



May 17, 1938. s. SCHILLER Re. 20,731

Reissued May 17, 1938 UNITED STATES PATENT OFFICE Traffic Signs &Signals, Inc., a corporation oi Delaware Paterson, N. J

Original No. 1,903,385, dated April 4, 1933, Serial No. 483,023:September. 19, 1930.

February 13, 1933.

Renewed Application for reissue April 1, 1935, Serial N0. 14,140

5Claims.

This invention relates to light-reflecting units of the class forexample, which are used in groups so as to form signs or warningnotices. According to the preferred form of my invention such a unit isformed so that in front-to-rear section its forward or refractingsurface is convex and elliptical or substantially so and its reflectingsurface comprises two stepped and laterally related portionsso arrangedthat the relatively forward one reflects rays refracted by one portionof the refracting surface and the other reflects rays refracted by aportion of said refracting surface having a greater radius than thefirst portion thereof. The object of this construction may be statedbriefly as follows: Of course by forming the refracting surfaceelliptical and arranging the two surfaces so as to bring to a focus onthe reflecting surface the rays from a light source locatedsubstantially straight ahead of or in axial alinement with the apex ofits ellipse, the reflecting power of the unit will be greater straightahead than if the refracting surface is spherical; in other words, inthe straight-ahead direction the intensity of the reflected ray-pencilwill be greater in the former case than in the latter. But if it isattempted to obtain from such a unit (as by forming its reflectingsurface spherical) reflection of rays emanating from alight source notin such axial alinement, or not straight ahead, there results a loss ofreflecting power from such a unit in the direction of a light source solocated,

and this loss increases rapidly the further the light-source is thusremoved, although if the refracting surface were also spherical no suchloss, or practically none, would ensue. accomplish by my invention,therefore, is to obtain that greater intensity of reflection straightahead which characterim an elliptical as compared with a sphericalrefracting surface and an appreciable lessening of the mentioned lossattendant on the positioning of the light source so that its rays aremore or less angularly related to the longitudinal axis of theelliptical refracting surface. For example, by my invention, a unit orbutton say in a warning sign at the roadside will reflect light from anapproaching headlight straight ahead to a greater distance than a unithaving a spherical refracting surface, and it will remain well visibleas the vehicle approaches and consequently assumes some position whichisangularly related to the longitudinal axis of the elliptical surface ofthe unit,

i. e., in which the vehicle has departed from the straight-aheadposition. Other advantages flow from my invention, due principally tothe. use of What I aim to 7,

an elliptical refracting surface, as that the whole lens is illuminatedrather than a centralportion thereof as in the caseof a spherical lensand that as viewed from an angular position a greater area ofillumination is presented.

In the drawing,

Figs. 1 and 2 are side and front elevations of a unit embodying theinvention;

Figs. 3 and 4 are longitudinal sections of the lens, the arrow linesindicating diagrammatically the incoming and outgoing rays;

Fig. 5 is a longitudinal sectional view unit on a smaller scale; 4

Figs. 6 to 9 show different forms which the units may take, these allbeing of the one-step p i.

Fig. 10 shows a similar section of a unit of the pluristep type; and rFig. 11 is a fragmentary front elevation, and

Fig. 12 a section on line I2--|2 of Fig. 11, of a tile embodying anumber of the units.

The lens I in Figs. 1 to 5 has a convex frontal of said refractingsurface 2 which is elliptical or sub-- lens, as in Figs. 6 to 9. InFigs. 1 to 6 the backsurface of the lens and the reflecting surface arein face to face contact throughout with each other, but this is notindispensable as shown by Figs. 7 to 9 and when they are thus not so theback of the lens may be variously shaped as planiform at 5, Fig. 7, orhollowed in some way', as at 6 and '7, Figs. 8 and 9 as required foreconomy in molding the glass of which thelens is formed and otherconditions.

The reflecting surface or medium is formed in part with a centralportion 8 properly distanced from the front of the lens so as tocoincide with the ideal focus a (or that point in the focal line of thelens 'of maximum focal concentration oi the rays, and which portionishere and preferably circular in front elevationsee dotted lines, Fig.2and has its center concidentwlth the focal line or with thelongitudinal axial line of the lens) and in part with a portion 8flanking'or lateral of the portion 8 and here surrounding or outwardlyconcentric thereto and stepped back with reference thereto. are herefurther concave and conform substantially to spheres.

Such portions 8 and 9 45 them each with a circumferential stop or shoul-The unit so formed will have a definite reflecting power or intensitystraight ahead with re. spect to a light source located straight aheador substantially in the longitudinal axial line of the lens, and ofcourse greater than if the unit presented a spherical refractingsurface. Without the stepping or portions of the reflecting surface ormedium on movement of the light source to a position angularly relatedto said axis there would result a loss of reflective power which, ifcarried to the extreme, would render the unit practically invisible uponthe extreme movement,

and this regardless of the radial distance the light source is from theunit; this is of course because the distance of the 'ideal focus fromthe retracting surface has increased due to the v gradual increase inradius of the refracting suror below or at one side or the otherthereof.

face from front to rear. But with the stepping, under the sameconditions this difficulty is over come and as illustrated by Fig. 4 theunit is effective to reflect light coming from a light sourceappreciably offset from the axial line of the unit. But without the stepin the reflector, the advantages of the lens having the convex andsubstantially elliptical refracting surface will be realized but to alesser degree.

As indicated, whereas it is preferable that the unit have the portion 9actually surrounding the portion 8 and consequently the refractingsurface 2 developed clear around the longitudinal axis in'the sectionof' an ellipse the invention is not limited to this detail which makesthe unit useful in reflecting light coming from a light source angularlyrelated to the axis of the unit and located in any position around saidaxis, as above vThe unit may have of course more than two of the steppedsurfaces as indicated by i 10 at Hi, which shows a lens with threesurfaces stepped in the same relation as already described and which inthis particular example is adapted to have silvering applied to its saidsurface, as in Fig. 5.

If the units are to be fitted. into holes in a plate or the like of asign it will be desirable to form der H to abut the plate.

But the lenses may be cast all in one piece, as shown by Figs. 11 and12, where at their bases or greatest transverse diameters they areintegral with a common plate of glass or equivalent transparent materiall3.

Having thus fully described my invention what I claim is:

' 1. A reflecting unit including, with a lens hav-' I ing a convex andsubstantially elliptical refracting surface, a reflecting medium back ofsaid surface having a portion thereof arranged and formed to reflectrays refracted by one portion of said surface and another portionthereof set relatively back and lateral of its first portion andarranged and formed to reflect rays refracted by a portion of saidsurface having a greater radius than the first-named portion of saidsurface.

2. A reflecting unit including, with a lens having a convex andsubstantially elliptical refracting surface whose longitudinal axisextends from front to rear of the unit, a reflecting medium back of saidsurface having a portion thereof arranged and formed to reflect raysrefracted by one portion of said surface and another portion thereof setrelatively back and lateral of the first portion and arranged and formedto reflect rays refracted by a portion of said surface having a greaterradius than the first-named portion of said surface.

3. A reflect-ing unit including, with a lens having a convex andsubstantially elliptical refracting surface whose longitudinal axisextends from front to rear of the unit, a reflecting medium back of saidsurface having a portion thereof arranged and formed to reflect raysrefracted by the substantially central forward portion of said surfaceand another portion thereof set back of. and surrounding the firstportion and arranged and formed to reflect rays refracted by thecircumferential portion of said surface back of its said central.forward portion.

4. A reflecting unit including, with a lens having a convex andsubstantially elliptical refracting surface, a reflecting medium'back ofsaid surface having a portion thereof arranged to reflect rays refractedby one portion of said surface and another portion thereof lateral ofits first portion and arranged to reflect rays re fracted by a portionof said surface having a greater radius than the first-named portion ofsaid surface.

5. A reflecting unit including a lens having a convex and substantiallyelliptical retracting surface, a reflector in rear of said refractingsurface and having a central portion positioned substantially at thefocus of incident rays parallel to the axis of said lens, and a marginalportion posi- 5 tioned substantially at the focus of parallel raysentering the marginal portion of said lens and inclined to the axisthereof.

' SIGGE SCHILLER.

